She had a knife aimed right at her heart, but Megan Jaufmann couldn't suppress a giggle. "Where is she?" the helmeted man with the knife demanded, gripping Jaufmann by the collar Thursday afternoon during a Pasco County Sheriff's Office training exercise. "Tell me where she is!" Jaufmann, 15, choked back her laugh and shouted back. "No! I don't know!" Seconds later, another man burst into the office at Sanders Memorial Elementary School, his gun in front of him. Just as Jaufmann's attacker raised his right fist to sink the tinfoil knife into her chest, several paintball bullets pinged off his black vest, leaving splashes of fluorescent pink.

"Awesome," said Cpl. Jeremy Colhouer approvingly. He told the school resource officer who had come to Jauffmann's rescue to hand his equipment off to another trainee.

"Yeah, he got me … this time," the mock stabber said, grinning.

A joking mood prevailed at the Sheriff's Office-sponsored active shooter training for 40 school resource officers, or SROs, drawn from the Pasco County Sheriff's Office, Dade City Police Department, Hernando County Sheriff's Office and New Port Richey Police Department.

The training session was designed to equip them for school shooter situations such as those at Columbine and Virginia Tech. Members of the Sheriff's Office Explorers, teens who receive training to possibly pursue a career in law enforcement, joined the scenarios as mock students.

The SROs milled around in fluorescent orange traffic control vests, wondering where they could find air conditioning and trading stories of their worst paintball injuries. A hit from a paintball bullet stings, even through a padded vest.

Did they prefer playing the good guys or the bad guys, as the role-playing officers and shooters were called?

"They're both fun," SRO Joe Kwiatkowski said.

But they turned serious when they ran the shooting scenarios, one by one.

Before the Columbine shootings, police officers were taught to set up a perimeter and call for a SWAT team, said Lt. J.R. Law, one of the trainers. But the 1999 killings sparked a nationwide change in thinking, he said: SWAT teams often take too long to arrive. School police officers must stop the shooter right away.

"It doesn't take long to kill a lot of people," Law said. "The shooter's focus is going to be on the students. Your victims are going to grow by the second if you don't intervene."

The Sheriff's Office began designing this type of training in July, he said, although SROs are trained annually to respond to shooter situations to reflect new tactics.

The Sanders Elementary building, which is slated for demolition, made a good training ground, Law said, standing in a sunny courtyard that served as the site of the first shooter scenario.

"They're gonna come in and eliminate the threat," the trainer, Cpl. Michael Sims, instructed the role-player. "Which is you."

As soon as Sims gave the sign to begin, the mock shooter burst into the courtyard, firing indiscriminately at the mock students standing by some bushes. In a second, three students were down.

A SRO skidded around the corner of the building, bypassing the students on the ground. He popped five paintball bullets at the shooter, who fell heavily to his knees and lay down on the walkway.

"There's no warning, no second chance," Law said from a safe distance away. "We're gonna eliminate the threat and talk later."